It has been reported that the injection of thymic cell-free extracts can restore the immunological function of neonatally thymectomized mice to reject skin grafts. Data showing partial reconstitution of neonatally thymectomized mice by thymus grafts in a Millipore chamber has suggested that the thymus acts as an endocrine gland and elaborates a hormone into the blood circulation. [See D. Osoba, et al., Nature 199, 359 (1963)]. This medicinally useful hormone has been isolated and is believed to be a polypeptide having the amino acid sequence: &lt;Glu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn. [See Bach et al., Comptes Rendes, 283 No. 14, 1605-1609 (1976)].
In general, the hormone is obtained in small quantities from pig blood by a laborious process involving defibrination, dialysis and concentration on a suitable filter followed by fractionation through a molecular sieve, chromatography on an ion-exchange resin followed by further fractionation by thin layer chromatography and finally by electrophoresis. Each step of the isolation is monitored by a bioassay which is based on the property of the peptide which inhibits the formation of rosettes in the presence of azathioprine.
The novel polypeptide obtained by the above process is useful in the treatment of autoimmune diseases such as lupus like pathology and specifically for the treatment of Lupus Erythematosus in man and for selectively stimulating T-cell activity in aging subjects.
According to the process of the present invention the peptide, &lt;Glu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn, is readily prepared in large quantities by chemical means.